This invention is directed to a generator testing appliance that assists a service technician when servicing an electrical power generation unit and more particularly is directed to an electrical circuit that the service technician electrically interposes in connection between an electrical generator and its controller in order to facilitate making measurements of electrical parameters of the circuit. With the generator testing appliance of the invention the service technician is able to analyze and diagnose the generator more quickly, more conveniently and with enhanced safety, when working to find a fault that is causing the generator to malfunction.
Referring to FIG. 1, a typical modern prime and standby electrical power generation unit 10 comprises an electromechanical generator 12 having stator and rotor windings that are connected to a controller 14. The electromechanical generator 12 is driven by an engine, such as a propane or gasoline fueled internal combustion engine 16. The controller 14 both senses voltage and/or current parameters from the windings and adjusts and controls other voltage and/or current parameters of the windings. Commonly, selected internal circuit nodes of the controller 14 are electrically connected to controller electrical terminals that may be connected to a manually separable controller connector 18. Similarly, selected internal circuit nodes of the electromechanical generator 12 are electrically connected through a cable 20 to generator electrical terminals that are connected to a manually separable generator connector 22 that mates with the controller connector 18. During normal generator operation, the generator 12 and controller electrical terminals are connected together either by directly connecting their respective connectors 18 and 22 to each other or by cables or other conductors that have connectors at their opposite ends that mate with the connectors of the generator and controller terminals. The term “cable” is used to refer to a group of multiple conductors whether or not they are bundled together by being enveloped in a surrounding cover or sheath.
When a generator malfunctions, a technician is called in to diagnose the problem and make an appropriate repair. In order to perform a diagnosis, the technician must perform a series of tests. Most generator manufacturers have manuals that describe recommended tests for troubleshooting problems. For most tests the technician uses a multimeter to read voltage and/or current values at a pair of generator terminals. Although some tests are performed with the generator connected to the controller in the same state as when the generator is operating normally, many tests require that the test be performed after disconnecting one or more electrical connections between the generator and the controller. That is where the problem begins that is solved by the invention.
As now practiced by generator technicians, the manner in which the technician performs the tests that require the disconnection of one or more conductors between the generator terminals and the controller terminals is to manually disconnect the appropriate conductor or disconnect the entire interconnecting cable 20. Then the technician must improvise some temporary connections of selected conductors between the generator and the controller and connect multimeter probes to the terminals as instructed by the manufacturer's manual so the technician can then read measured values. To perform the next test the technician may reconnect the initially disconnected conductor(s) and disconnect one or more others and take the next multimeter reading according to the instructions. Some tests require the disconnection and subsequent reconnection of multiple conductors. The technician usually must repeat this process several times. To do so, each time the technician must reach into the housing for these components, take the time to physically make specific connections and disconnections and then manually hold or attach the multimeter probes in contact with the appropriate terminals or cable ends. Often the appropriate terminals or cable ends are in an inconvenient location where it is difficult to make the appropriate probe contact and/or to hold the probe in continuous contact while reading the multimeter. Sometimes the technician must improvise temporary electrical connections with some kind of jumper or other temporary on-site constructed wiring somewhat like making breadboard connections on an experimental circuit but without easy access to the circuit nodes. These temporary wired connections must also be dismantled before performing the next recommended test.
Performing the above sequence of manual manipulations is not only difficult and time consuming but also often exposes the technician to serious electrical shock hazard especially if the generator is operating while the technician performs these manual manipulations. The purpose and object of this invention is to avoid these problems by making the physical actions for opening and closing selected individual circuits and for connecting the multimeter probes considerably faster, easier and safer. Not only does the invention avoid the described problems but the simplification of the process of connecting and disconnecting circuit connections and properly positioning the multimeter probes also allows the technician to better concentrate and focus on the technical significance of the multimeter readings. Additionally, the invention decreases or eliminates the risk of damaging the terminals of the connectors that can be caused by inserting meter test lead probes directly into the terminals of the connectors.
The prior art has developed some circuits in separate cabinets that connect by cables to a generator for purposes of diagnosis and fault analysis. However, these devices are not interposed between the generator and its controller. They do not maintain the same interconnection circuit paths directly between the generator and the controller that exist during normal operation of the electrical power generation unit. Instead they have internal circuitry (and in some cases have their own data processor and software) that is used as a substitute for all or at least a part of the circuitry that is normally associated with the installed electrical power generation unit. They become a temporary and substitute part of the generator's control system. Consequently the tests are not performed using the generator's own controller. Other prior art exists that connects meters to the generator but also is not interposed between the generator and its associated controller and do not maintain the same interconnection circuit paths that exist during normal operation